AE 451 Aeronautical Engineering Design - Department of ...

AE 452
Aeronautical Engineering Design II
Cost Analysis
Prof. Dr. Serkan Özgen
Dept. Aerospace Engineering
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Problems when estimating cost
Number of parameters involved (technical, financial,
political)
Type of money to be used
Then year dollars: actual dollars spent in each year of the
program; past, present and future. For future program costs an
estimation of the inflation rate must be made.
Constant year dollars: actual dollars spent normalized by
inflation factors for some selected year.
Aircraft production quantity and rate; the more aircraft
produced, the more manufacturer learns and aircraft
can be produced cheaper (learning curve effect).
Each time the production quantity is doubled, the
labor cost per aircraft goes down by ~20 %.
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Production learning curve
3

Elements of life cycle cost
4

Elements of life cycle cost
RDT&E (Research, Development, Test and
Evaluation): technology research, design
engineering, prototype fabrication, flight and
ground testing and evaluations for
operational suitability. RDT&E costs are fixed
costs (non-recurring costs).
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Elements of life cycle cost
Flyaway (production) costs: labor and
material costs to manufacture the airplane
including the airframe, engines and avionics.
Includes production tooling (jigs, fasteners,
molds, etc.), manufacturer’s overhead and
administrative expenses. Production costs
are recurring.
6

Elements of life cycle cost
Program cost: the total cost to develop and
deploy a new airplane into the inventory
(mostly military). Some aircraft require
special gound facilities for operational
deployment.
7

Elements of life cycle cost
Operations and maintenance: covers fuel, oil,
aircrew costs, maintenance, insurance and
depreciation.
Disposal: getting rid of the airplane after its
useful life has ended.
8

RDT&E and Production Costs
(DAPCA IV model)
Development and Procurement Costs of Aircraft Model
is a cost estimation relationship model and it
estimates the hours required for RDT&E and
production by the engineering, tooling,
manufacturing and quality control groups.
These are multiplied by hourly rates to yield
costs.
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RDT&E and Production Costs
(DAPCA IV model)
Engineering hours: include airframe design
and analysis, test engineering, configuration
control and systems engineering.
Tooling hours: includes preparation for
production. Design and fabrication of tools
and fixtures, production of molds,
programming CAD/CAM tools, development
and fabrication of production test apparatus.
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RDT&E and Production Costs
(DAPCA IV model)
Manufacturing hours: direct labor to fabricate
the aircraft; forming, machining, fastening,
subassembly fabrication, final assembly,
routing (hydraulic, electric and pneumatic
lines) and purchased part installation
(engines, avionics, sub-sytems, etc.)
Quality control: includes receiving inspection,
production inspection and final inspection.
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RDT&E and Production Costs
(DAPCA IV model)
Flight test costs: all costs to demonstrate
airworthiness and/or compliance with military
standards except for the costs of the flight
test airplanes themselves.
Manufacturing materials: raw materials and
purchased hardware and equipment from
which the airplane is built (aluminum,
composites, electric, hydraulic, pneumatic
systems, fasteners, etc.)
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DAPCA IV Cost Model
(cost in constant 1999 Dollars)
Engineering hours, H e=7.07 W e 0.777 V 0.894 Q 0.163
Tooling hours, H t=8.71 W e 0.777 V 0.696 Q 0.263
Manufacturing hours, H m=10.72 W e 0.82 V 0.484 Q 0.641
Quality control hours, H q=0.076 H m (cargo airplanes)
H q=0.133 H m (all others)
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DAPCA IV Cost Model
(cost in constant 1999 Dollars)
Development support costs, C D=66 W e 0.630 V 1.3 ,
Include fabrication of mockups, subsystem
simulators, structural and other test items.
Flight test costs, C F=1807.1 W e 0.325 V 0.282 FTA 1.21
Q: smaller of production quantity or number to be
produced in 5 years,
FTA: number of flight test airplanes.
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DAPCA IV Cost Model
(cost in constant 1999 Dollars)
Engine production cost,
C ENG=2251(0.043T max + 243.25M max + 0.969T turbine inlet - 2228)
Increase by 15-20% for a turbofan engine.
Manufacturing materials cost,
C M=16 W e 0.921 V 0.621 Q 0.799
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DAPCA IV Cost Model
(cost in constant 1999 Dollars)
RDT&E + production costs
= HeRe+ HtRt+HmRm+HqRq +CD+CF+CM+CengNeng+Cavionics 16

DAPCA IV Cost Model
(cost in constant 1999 Dollars)
Recommended fudge factors:
Aluminum: 1.0,
Graphite-epoxy: 1.1-1.8,
Fiberglass: 1.1-1.2,
Steel: 1.5-2.0,
Titanium: 2.0.
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DAPCA IV Cost Model
(cost in constant 1999 Dollars)
Average wrap rates (employee salary+employee
benefits+overhead+administrative costs)
R e = $ 86 / h,
R t = $ 88 / h,
R m = $ 81 / h,
R q = $ 73 / h.
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DAPCA IV Cost Model
(cost in constant 1999 Dollars)
Avionics costs = 5-25% of flyaway cost
or $3000–6000/lb,
Investment cost factor = 1.1-1.4 * predicted flyaway
cost,
Initial spares = 10-15% purchase price.
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Operations and maintenance costs
Military aircraft:
Fuel costs 15 %,
Crew salaries 35 %,
Maintenance 50 %.
Civil aircraft:
Fuel costs 38 %,
Crew salaries 24 %,
Maintenance 25 %,
Depreciation 12 %,
Insurance 1 %.
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Fuel and oil costs
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Crew salaries - civil
Block hours: the total time the aircraft is in use,
from when the blocks are removed from the
wheels at the departure airport to when they
are placed on the wheels at destination.
Block speed: trip distance/block time 1400 miles,
= (0.015+7/D) if D < 1400 miles.
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Crew salaries - civil
Crew cost/block hour (1999 prices):
Two man crew = 51(V cW o/10 5 ) 0.3 +122,
Three man crew = 68(V cW o/10 5 ) 0.3 +172.
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Crew salaries – military
Crew ratio: # of aircrews/aircraft:
Fighters: 1.1,
Transports: 3.5.
Crew cost/year = 2080*engineering hourly
wrap rate
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Maintenance expenses
MMH/FH: maintenance man hours/flight hour.
Labor costs:
≈MMH/FH*FH*manufacturing wrap rate,
Materials, parts and supplies costs:
Military aircraft ≈ labor costs,
Civil aircraft:
material cost Ca
C
3.
3
10.
2 58
6
FH 10
10
C : aircraft cost without
engine,
C
N
a
e
e
: cost per engine,
: number
of
engines.
e
6
19
N
25
e
,

Depreciation and insurance
Allocation of the purchase price over the
operating life of the aircraft,
If the resale value is 10% of the purchase
price and the depreciation period is 12 years:
Yearly depreciation = airframe cost*0.9/12.
Insurance = 1% cost of operations.
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